This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A081302 #6 Sep 08 2022 08:45:09
%S A081302 1,1,21,61,1891,9633,404713,2997541,159902271,1564345201,101406750589,
%T A081302 1236882490845,94479649710811,1382731226210881,121677107761110993,
%U A081302 2079381120597925237,207197254527662127511,4051708966720224576081
%N A081302 Subdiagonal of square array A081297.
%H A081302 Vincenzo Librandi, <a href="/A081302/b081302.txt">Table of n, a(n) for n = 0..200</a>
%F A081302 a(n) = ((n+3)^(n+1)-(-(n+2))^(n+1))/(2*n+5).
%t A081302 Table[((n + 3)^(n + 1) - (-(n + 2))^(n + 1)) / (2 n + 5), {n, 0, 20}] (* _Vincenzo Librandi_, Aug 08 2013 *)
%o A081302 (Magma) [((n+3)^(n+1)-(-(n+2))^(n+1))/(2*n+5): n in [0..20]]; // _Vincenzo Librandi_, Aug 08 2013
%Y A081302 Cf. A081298, A081299, A081300, A081301.
%K A081302 easy,nonn
%O A081302 0,3
%A A081302 _Paul Barry_, Mar 17 2003